The H&R bars are actually a bit MORE expensive for the bars themselves but do not require any additional drop links for the front bar because it's designed just like the stock 996 bar only bigger. Because it retains the stock configuration with the turn down at the end there are NO adjustments to this bar (4 adjustment holes in the GT3 bar). Also the H&R bars are solid whereas the GT3 bars are Hollow. What this means is that the H&R bars are much heavier. Without knowing the strength of the metal used in the H&R bars it's tough to say which one is actually stiffer esp since physical measurement for the H&R front bar is slightly smaller than the GT3 front bar. (.4 inch difference in diameter I believe). Comparing the front bars there's a good 15-20lb difference between the front GT3 bar and the front H&R bar.

Both rear bars are adjustable, 3 ways for the H&R and 5 ways for the GT3 bar. Again one is solid and one is hollow making the H&R bar again much heavier.

I have a weird setup on my car. I have the H&R clubsports and have the H&R front bar with a GT3 rear bar. It all works very well together but after a few track outings I'm almost wishing I would have gone with the GT3 front so that I have some adjustability to play with the car. I may still eventually go that route but want to learn the car better the way it sits first.

Yes, the GT3 front bar requires adjustable drop links. The rear does not - but take a look at the droplinks and you may want to get adjustables for the rear. If you are going for new front and rear sways, and new front droplinks, you might as well get the adjustable rears as well - also, they are cheaper than the fronts.

Like I said, the stock links are very skinny. If you don't track the car, I wouldn't worry; but if you do, you should seriously think of getting new links all around.

Adding GT3 bars and trg links made my ROW M030 handle even better. Less roll and a little stiffer. Plus, I can actually adjust the car's handling a bit.

See how in the pictures the front bar for your C4 has a straight end to it?...it's different on the C2. The end points downwards and because of the downward angle it's not possible to have multiple mounting holes for the bar. Thats why when you get the GT3 bar with it's straight bar end the different length (shorter) end links are required.

Here's a picture I found of the H&R front bar for a C2(except it's oriented upside down...)